Apparatus for pressure processing a pumpable food substance

ABSTRACT

An improved method and apparatus for pressure processing a pumpable substance are shown and described. In a preferred embodiment, a valve is coupled to a source of a pumpable food substance and a pressure vessel, the valve being movable to a first, second and third position. When the valve is in a first position, an inlet port in the valve is aligned with a passageway that is open to the pressure vessel. When the valve is in the second position, the valve body seals the passageway, and when the valve is in the third position, an outlet port provided in the valve is aligned with the passageway. The valve is therefore moved to a first position to allow a volume of pumpable substance to be forced into the pressure vessel, the valve is moved to a second position to seal the passageway while the pumpable substance is pressurized to a selected pressure for a selected period of time to achieve a desired result, and the valve is then moved to a third position to allow the treated, pumpable substance to be discharged from the pressure vessel. The inlet port and the outlet port are provided with low-pressure seals, and high-pressure seals are provided in the valve such that when the valve is in the second position, the passageway is sealed by the high-pressure seals. By separating the low-pressure and high-pressure regions and functions of the valve, high-pressure containment is simplified, and it is possible to use relatively large passageways, thereby increasing the flow rate and variety of substances that may be processed.

TECHNICAL FIELD

This invention relates to an improved method and apparatus for pressureprocessing a pumpable food substance or the like.

BACKGROUND OF THE INVENTION

Many objectives may be achieved by exposing a pumpable substance, forexample, any pumpable food substance, to ultrahigh-pressure. Forexample, many fresh food products may be pasteurized by exposing them toultrahigh-pressure for a selected amount of time, thereby killingmicroorganisms. Ultrahigh-pressure may also be used to render a desiredphysical change in a food product, for example, to improve moistureretention, to cause gelation of starchy suspensions, or to raise themelting point of butter and soft fats. Ultrahigh-pressure processing maybe used to improve the quality of existing products, and to generate newproducts.

Currently, the majority of pressure-based food processing is achieved byloading a food product into a large pressure vessel. Typically, the foodis prepackaged in flexible packets. The pressure vessel is then closedand pressurized to a selected pressure. This pressure is maintained fora selected amount of time, commonly referred to as the "dwell time," toachieve the desired physical change in the food product. The vessel isthen depressurized, and the contents unloaded.

Although current systems produced desirable results, they also haveseveral disadvantages. For example, large pressure vessels are costly toconstruct. These current systems are also time consuming to use, giventhe nature of the processing.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved ultrahigh-pressure method and apparatus for processing apumpable substance.

It is another object of this invention to provide in a preferredembodiment an improved ultrahigh-pressure method and apparatus forprocessing a pumpable food substance that is less expensive to use thancurrently available systems.

It is another object of this invention to provide in a preferredembodiment a faster and more efficient method and apparatus forprocessing a pumpable food substance.

These and other objects of the invention, as will be apparent herein,are accomplished by providing an improved ultrahigh-pressure system thatprocesses a pumpable substance, such as a food product, preferably on acontinuous basis. In a preferred embodiment, a valve is coupled to asource of a pumpable substance to be treated, and to a pressure vessel.The valve is moveable to a first, second and third position. The valveis comprised of three segments, and has an inlet port in a firstsegment, and an outlet port in a third segment. In a preferredembodiment, the valve is slidably movable along a shaft that passesthrough a longitudinal axis of the valve, a passageway being provided inthe shaft that is open to the pressure vessel. When the valve is in thefirst position, the inlet port is aligned with the passageway, therebyallowing a volume of pumpable substance to flow through the inlet portand passageway into the pressure vessel. The valve is then slid alongthe shaft to the second position, thereby sealing the passageway againstthe valve. The pumpable substance is then pressurized to a selectedpressure for a selected period of time, depending on the desired result,after which the pumpable substance is depressurized.

The valve is then moved to the third position, thereby aligning theoutlet port with the passageway and allowing the pumpable substance tobe discharged from the pressure vessel.

In a preferred embodiment, the pressure vessel has a chamber that isdivided into a first region and a second region by an isolating memberthat is sealed along the width of the pressure chamber and that is freeto move or expand and contract along the length of the pressure chamber.As the volume of pumpable substance flows into the first region of thechamber, it pushes the isolating member along the length of the chamberto accommodate the volume of pumpable substance.

In a preferred embodiment, a pressurizing medium such asultrahigh-pressure fluid, is introduced into the second region of thechamber via a second valve, the ultrahigh-pressure fluid acting on theisolating member which in turn compresses and pressurizes the pumpablesubstance. The second valve is moveable to a first and second positionand is comprised of a first and second segment. A port is provided inthe first segment, which is aligned with a second passageway that isopen to the second region of the chamber, when the second valve is in afirst position. When the second valve is moved to a second position, thesecond passageway is sealed by the second valve. The second passagewayis coupled to a source of ultrahigh-pressure fluid.

Therefore, a volume of ultrahigh-pressure fluid is introduced throughthe second passageway into the second region to pressurize the pumpablesubstance as described above, while the second valve is in the secondposition. After a selected amount of time, the pressure is released byallowing a quantity of the ultrahigh-pressure fluid to flow out of thesecond region, and the second valve is moved to a first position. Avolume of low-pressure fluid is introduced through the port and flowsthrough the second passageway into the second region, thereby acting onthe isolating member and discharging the pumpable substance from thechamber, the pumpable substance exiting through the first passageway andthe outlet port of the first valve, the first valve being in its thirdposition.

In a preferred embodiment, low-pressure seals are provided on opposingsides of each of the inlet and outlet ports of the first valve, and onopposing sides of the port of the second valve. Two high-pressure sealsare provided in the second segment of each of the first and secondvalves, such that when the first and second valves are in theirrespective second positions, the two high-pressure seals of each valveare positioned on opposing sides of the first and second passageways,respectively, thereby sealing the passageways.

By providing a system in accordance with a preferred embodiment of thepresent invention, it is possible to use ports and passageways havingrelatively large inner diameters, thereby allowing the processing ofviscous food products, food products containing solid inclusions, and toallow high flow rates of low viscosity fluids, while still adequatelysealing against the ultrahigh-pressures. Conventional ultrahigh-pressuresystems use tubing having a much smaller inner diameter and conventionalultrahigh-pressure valve seats. If the ultrahigh-pressure valve andtubing are scaled up to accommodate viscous food products, highseparation forces are generated at the ultrahigh-pressure shut off valveseats. In the preferred embodiment of the present invention illustratedherein, the ultrahigh-pressure valve seats are eliminated, therebysimplifying the high-pressure containment and allowing the use of largepassageways and high flow rates into and out of the pressure vessel.

In a preferred embodiment, multiple systems as described above arecoupled together in parallel, thereby processing large volumes ofpumpable substance in a fast, cost effective manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional elevational view of a valve provided inaccordance with a preferred embodiment of the present invention.

FIG. 2 is a partial cross-sectional elevational view of a system forprocessing a pumpable substance provided in accordance with a preferredembodiment of the present invention.

FIGS. 3-6 are conceptual, cross-sectional elevational views of a systemprovided in accordance with a preferred embodiment of the presentinvention, in four different stages of operation.

FIG. 7 is a conceptual, cross-sectional elevational view of a systemprovided in accordance with an alternative embodiment of the presentinvention.

FIG. 8 is a conceptual, cross-sectional elevational view of a systemprovided in accordance with an alternative embodiment of the presentinvention.

FIG. 9 is a diagram illustrating the steps of a preferred embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

Many objectives may be achieved by processing a pumpable substance, forexample, a pumpable food substance such as soup, jam, or fruit juice,with ultrahigh-pressure. Such pressure processing may be used, forexample, to pasteurize a food product, or to render a desired physicalchange that can be accomplished by pressurizing the food substance to aselected pressure for a selected period of time. Although the selectedpressure and dwell time required to achieve a desired result will varywith the desired result and the given food substance, pressures in therange of 40,000-130,000 psi may be used. The selected pressure and dwelltime to achieve a desired result in a given food substance is known fora variety of food products to one of ordinary skill in the art, or maybe determined without undue experimentation.

A preferred method and apparatus for pressure processing a pumpablesubstance is provided in accordance with a preferred embodiment of thepresent invention. As illustrated in FIG. 1 and conceptually illustratedin FIGS. 3-6, the pressure processing system 10 includes a first valve12 having a valve body 16 that is movable to a first position 18, secondposition 20, and third position 22. Although valve 12 may be moved tothese three positions by any appropriate means such as a motor orscrewdrive, in a preferred embodiment, valve 12 is moved to a selectedposition by air cylinder 11.

As illustrated in FIGS. 1 and 3-6, the valve 12 has an inlet port 24 andan outlet port 26. When the valve 12 is in the first position 18, inletport 24 is aligned with passageway 28 which in turn is open to a chamber44 of pressure vessel 30. Inlet port 24 is coupled to a source ofpumpable substance 14, such that when the valve 12 is in the firstposition 18, a volume of pumpable substance 14 may be forced intopressure vessel 30. The valve 12 further has an outlet port 26 that isaligned with the passageway 28 when the valve is in the third position22. When the valve 12 is in the second position 20, the valve body 16seals passageway 28. In a preferred embodiment, valve 12 is slidablymovable along a first shaft 32 that passes through a longitudinal axisof the valve. The passageway 28 is provided in the first shaft 32.

In a preferred embodiment, valve 12 is comprised of a first segment 34,a second segment 36, and a third segment 38, the inlet port 24 beingprovided in the first segment 34 and the outlet port 26 being providedin the third segment 38. As further illustrated in FIGS. 1 and 3-6,low-pressure seals 40 are provided on opposing sides of both the inletport 24 and outlet port 26, and two high-pressure seals 42 are providedin the second segment 36. As illustrated in FIGS. 4 and 5, when thevalve 12 is in the second position 20, the passageway 28 is aligned withthe second segment 36 such that the high-pressure seals 42 are providedon opposing sides of passageway 28. In a preferred embodiment, thehigh-pressure seals 42 are spaced apart by a distance equal to at leasttwo times the inner diameter of passageway 28, thereby reducing thestress concentration near the entrance 13 of passageway 28. As a result,fatigue damage is reduced and the life of shaft 32 is increased.

To further ensure proper pressure containment, the ratio of the outerdiameter 27 to the inner diameter 29 of the high-pressure second segment36 is at least 2.5 to 1, with preferred results being achieved when theratio is 3 to 1. The first and third segments 34 and 38 are low-pressuresegments and may therefore be made with lower strength materials or witha thinner wall thickness, for example, having an outer diameter to innerdiameter ratio that is less than 2.5.

By providing a valve in accordance with the preferred embodiment of thepresent invention, the high-pressure region and function is separatedfrom the low-pressure regions and functions, thereby allowing the use ofan inlet port 24, outlet port 26, and passageway 28 having a relativelylarge inner diameter, as compared to conventional ultrahigh-pressuretubing. More particularly, a conventional ultrahigh-pressure system usesplumbing lines having a small inner diameter, on the order of 1/8 inch,as well as high-pressure valve seats such as poppet valves. Aconventional system is therefore incapable of handling viscoussubstances or substances having solid inclusions, or high flow rates ofnon-viscous fluids. If a conventional ultrahigh-pressure system werescaled up in size to accommodate these type of systems and operatingconditions, high separation forces are generated at the high-pressureshut-off seats, thereby increasing the size and cost of the valve. Inthe preferred embodiment of the present invention illustrated herein,however, the ultrahigh-pressure valve seats are eliminated, the pressureforces being transferred to the strong, cylindrical second segment 36.High-pressure containment is therefore simplified, thereby allowing theuse of relatively large passageways and high flow rates into and out ofthe pressure vessel 30. Although in a preferred embodiment an innerdiameter of the inlet port 24, outlet port 26, and passageway 28 is0.25-1.0-inch, it will be understood by one of ordinary skill in the artthat the system described may be scaled up to accommodate larger innerdiameters.

In a preferred embodiment as illustrated in FIGS. 2-6, the pressurevessel 30 has a chamber 44 that is divided into a first region 50 and asecond region 52 by a bladder 15 that is fixed at a first end 19 ofchamber 44 and that is free to expand and contract longitudinally alongthe length of the chamber. Therefore, as a volume of pumpable substance14 is forced into the first region 50, the pumpable substance 14 actsagainst bladder 15, causing it to expand along the length of the chamberto accommodate and encapture the volume of pumpable substance. Apressurizing medium, such as ultrahigh-pressure fluid, is introducedinto the first region 50 to act against bladder 15 in the oppositedirection, thereby compressing and pressurizing pumpable substance 14 toa selected pressure, for a selected period of time. The bladdertherefore acts to isolate the pumpable substance from the pressurizingmedium and from the inner surface of the chamber 44. This will serve toprotect the pumpable substance from contamination, for example, frommixing with the pressurizing medium or from chemically reacting with theinner surface of the chamber.

In an alternative embodiment, as illustrated in FIG. 7, a bellows 17 iscoupled to the first end 19 of chamber 44 and is free to expand andcontract along the length of the chamber to accept, pressurize anddischarge the pumpable substance. In a second alternative embodiment, asillustrated in FIG. 8, a piston 46 is provided in the chamber 44. Thepiston is sealed along the width of the chamber by seal 48, and is freeto move longitudinally along the length of the chamber. In analternative embodiment, the inner surface of the chamber is coated toinhibit corrosion, for example by chrome or nickel plating.

In a preferred embodiment, as illustrated in FIGS. 2-6, a second valve54 is provided, that is movable to a first position 60 and secondposition 62. The second valve 54 is provided with a port 66 that isaligned with a second passageway 56, when the second valve 54 is in thefirst position 60. Similar to the first valve 12, the body of the secondvalve 54 seals the second passageway when the second valve is in thesecond position 62. In a preferred embodiment, the second valve 54 isslidably movable along second shaft 70 which extends through alongitudinal axis of the second valve 54, the second passageway 56 beingprovided in the shalt 70. For ease of disassembly for cleaning andservicing, or to allow the use of different materials to minimize cost,the second valve 54 may be provided in a first segment 72 and a secondsegment 74. As illustrated in FIGS. 2-6, the second passageway 56 is influid communication with the second region 52 of chamber 44 and iscoupled to a source of ultrahigh-pressure fluid 58 via second port 76.

Therefore, as illustrated in FIGS. 3 and 7, a pumpable substance may bepressure processed in accordance with a preferred embodiment of thepresent invention by positioning the first valve 12 in the firstposition 18, such that the inlet port 24 coupled to the source ofpumpable substance 14 is aligned with the first passageway 28, step 78.The second valve 54 is positioned in its first position 60 such that theport 66 is aligned with the second passageway 56, step 80. A volume ofpumpable substance 14 is then forced through the inlet port and thefirst passageway into the first region 50 of the chamber 44 of thepressure vessel 30, the pumpable substance 14 forcing the bladder 15 tomove longitudinally in the chamber as necessary to accommodate thepumpable substance, step 82. It should be noted that during this step,fluid located on the opposite side of the bladder in the second region52 of the chamber will be discharged through the port 66 as the pumpablesubstance is introduced into the first region 50.

After the first valve 12 and the second valve 54 are moved to theirrespective second positions to seal the first passageway 28 and thesecond passageway 58, respectively, steps 84 and 86, the pumpablesubstance is pressurized to a selected pressure for a selected period oftime, step 88. In a preferred embodiment, as illustrated in FIG. 4, thisis achieved by forcing a volume of ultrahigh-pressure fluid into thesecond region 52 via the second port 76. After the pumpable substancehas been pressurized to the selected pressure for a selected period oftime, the pumpable substance is depressurized, for example, by allowinga quantity of the ultrahigh-pressure fluid to flow out of the secondregion, step 90, as illustrated in FIG. 5.

As illustrated in FIG. 6, the first valve 12 is moved to the thirdposition 22 and the second valve 54 is moved to the first position 60,steps 92 and 94. A volume of low-pressure fluid is forced through theport 66 of the second valve 54, the low-pressure fluid passing throughthe second passageway 56 into the second region 52 to act on the bladder15, thereby discharging the pumpable substance 14 from the pressurevessel 30 through the outlet port 26 of the first valve 12, step 96.

It will be understood that the second valve 54 may alternately beprovided with two low-pressure segments and a high-pressure segment,similar to the first valve 12, with a second low-pressure port beingprovided in the third segment. The second low-pressure port may be usedto discharge fluid from the second region 52 of the chamber as pumpablesubstance is introduced into the first region 50, with port 66 beingused to introduce a volume of low-pressure fluid into the second region52 to discharge the pumpable substance 14, or vice versa.

An improved method and apparatus for pressure processing a pumpablesubstance has been shown and described. From the foregoing, it will beappreciated that although embodiments of the invention have beendescribed herein for purposes of illustration, various modifications maybe made without deviating from the spirit of the invention. Thus, thepresent invention is not limited to the embodiments described herein,but rather is defined by the claims which follow.

We claim:
 1. Apparatus for pressure processing a pumpable foodsubstance, comprising:a source of a pumpable food substance; a pressurevessel; means for pressurizing and depressurizing the pumpable foodsubstance while it is in the pressure vessel; and a valve that ismovable to a first, second and third position, the valve having an inletport coupled to the source of the pumpable food substance, and an outletport, such that when the valve is moved to the first position, the inletport is aligned with a passageway that is open to the pressure vesseland a volume of the pumpable food substance may flow into the pressurevessel via the inlet port and the passageway, when the valve is moved tothe second position, the passageway is sealed and the pumpable foodsubstance is pressurized to a selected pressure for a selected period oftime after which it is depressurized, and when the valve is moved to thethird position, the outlet port is aligned with the passageway, therebyallowing the pumpable food substance to be discharged from the pressurevessel.
 2. The apparatus according to claim 1 wherein the valve isslidably movable along a shaft that passes through a longitudinal axisof the valve, the passageway being provided in the shaft.
 3. Theapparatus according to claim 1 wherein the inlet port, the outlet portand the passageway all have an inner diameter of 0.25-1.0-inch.
 4. Theapparatus according to claim 1 wherein the valve further comprises afirst, second and third segment, the inlet port is provided in the firstsegment, with first and second low-pressure seals being provided onopposing sides of the inlet port, first and second high-pressure sealsare provided in the second segment, and the outlet port is provided inthe third segment, with third and fourth low-pressure seals provided onopposing sides of the outlet port.
 5. The apparatus according to claim 4wherein the passageway is aligned with the second segment of the valvewhen the valve is moved to the second position, such that the first andsecond high-pressure seals are positioned on opposing sides of thepassageway.
 6. The apparatus according to claim 5 wherein the first andsecond high-pressure seals are spaced apart by a distance equal to atleast two times the inner diameter of the passageway.
 7. The apparatusaccording to claim 4 wherein a ratio of an outer diameter of the secondsegment to an inner diameter of the second segment is at least 2.5. 8.The apparatus according to claim 1 wherein the pressure vessel has achamber and an isolating member that divides the chamber into a firstregion and a second region, the volume of the first and second regionsvarying as the isolating member moves, the pumpable food substanceflowing through the inlet port and the passageway into the first region,and wherein a pressurizing medium is forced into the second region topressurize the pumpable food substance to a selected pressure andallowed to flow out of the second region to depressurize the pumpablefood substance.
 9. The apparatus according to claim 8 wherein a secondvalve is coupled to a second passageway that is open to the secondregion and that is coupled to a source of ultrahigh-pressure fluid, thesecond valve being movable to at least a first and second position, thesecond valve having a port that is coupled to a source of low-pressurefluid and that is aligned with the second passageway when the valve isin the first position, the second passageway being sealed when thesecond valve is in the second position, such that when the secondpassageway is sealed, ultrahigh-pressure fluid flows through the secondpassageway into the second region, thereby pressurizing the pumpablefood substance to a selected pressure for a selected period of time, avolume of the ultrahigh-pressure fluid being allowed to flow out of thesecond region, the second valve being moved to the first position suchthat a volume of low-pressure fluid flows through the port of the secondvalve, through the second passageway and into the second region where itacts on the isolating member to force the pumpable food substance out ofthe first region through the first passageway and the outlet port of thefirst valve.
 10. The apparatus according to claim 9 wherein the secondvalve is slidably movable along a second shaft that passes through alongitudinal axis of the second valve, the second passageway beingprovided in the second shaft.
 11. The apparatus according to claim 9wherein the second valve further comprises a first and second segment,the port is provided in the first segment with first and secondlow-pressure seals being provided on opposing sides of the port, andfirst and second high-pressure seals are provided in the second segment.12. The apparatus according to claim 9 wherein the second valve ismovable to a third position and comprises a first, second, and thirdsegment, the port being provided in the first segment and a secondlow-pressure port being provided in the third segment, such that whenthe second valve is in the third position, the second low-pressure portis aligned with the second passageway, thereby allowing the low-pressurefluid to be discharged from the second region via the second passagewayand the second low-pressure port.
 13. The apparatus according to claim11 wherein the second passageway is aligned with the second segment ofthe second valve when the second valve is moved to the second position,such that the first and second high-pressure seals are positioned onopposing sides of the second passageway.
 14. The apparatus according toclaim 8 wherein the isolating member is a bladder that is free to expandand contract along the length of the chamber.
 15. The apparatusaccording to claim 8 wherein the isolating member is a bellows that isfree to expand and contract along the length of the chamber.
 16. Theapparatus according to claim 8 wherein the isolating member is a pistonthat is free to move along the length of the chamber.
 17. The apparatusaccording to claim 16 wherein an inner surface of the chamber is coated.18. Apparatus for pressure processing a pumpable food substance,comprising:a source of pumpable food substance; a pressure vessel havinga chamber and an isolating member that divides the chamber into a firstregion and a second region, the volume of the first and second regionsvarying as the isolating member moves; means for allowing a volume ofpumpable food substance to selectively flow into and out of the firstregion; and a valve coupled to a passageway that is open to the secondregion and that is coupled to a source of ultrahigh-pressure fluid, thevalve being movable to a first and second position, the valve having aport that is coupled to a source of low-pressure fluid and that isaligned with the passageway when the valve is in the first position, thepassageway being sealed when the valve is in the second position, suchthat when the passageway is sealed, ultrahigh-pressure fluid flowsthrough the passageway into the second region, thereby pressurizing thepumpable food substance to a selected pressure for a selected period oftime, a volume of the ultrahigh-pressure fluid being allowed to flow outof the second region, the valve being moved to the first position suchthat a volume of low-pressure fluid flows through the port of the valvethrough the passageway and into the second region where it acts on theisolating member to discharge the pumpable food substance from the firstregion of the pressure vessel.